dbi-dbrc

Description

This is essentially a database connection configuration library, allowing you to avoid hard-coding passwords in your programs, and store other generalized information, when making database connections.

It can also be used as a general password storage manager for other types of connections, e.g. ssh, ftp, etc.

The name was originally based on the old DBI library (which in turn was based on the Perl library of the same name), and was originally meant as a supplement to that library. The DBI library is now defunct, but it not necessary to use this library. But, that explains why there's an outer "DBI" namespace module.

Requirements

• gpgme - For GPG encrypted files (which you should be doing).

For MS Windows there are these additional requirements:

• sys-admin
• win32-file-attributes
• win32-dir
• win32-process

Installation

gem install dbi-dbrc

Synopsis

require 'dbi/dbrc'

dbrc = DBI::DBRC.new('mydb') # or...
dbrc = DBI::DBRC.new('mydb', 'someUser')

puts dbrc.db
puts dbrc.user
puts dbrc.driver
puts dbrc.timeout
puts dbrc.max_reconn
puts dbrc.interval
puts dbrc.dsn

Notes on the .dbrc file

This module relies on a file somewhere on your filesystem (normally your home directory) called ".dbrc", and it is meant to be analogous to the ".netrc" file used by programs such as telnet. The .dbrc file has several conditions that must be met by the module or it will fail:

• Permissions must be set to 600 (Unix only).
• Must be hidden (MS Windows only).
• Must be owned by the current user.
• Must have database, user and password. Other fields are optional.
• Must be in the following space-separated format (in the 'plain' version):

  database user password driver timeout maximum_reconnects interval
  # e.g. mydb     dan    mypass     oracle   10        2         30

You may include comments in the .dbrc file by starting the line with a "#" symbol.

A failure in any of the rules mentioned above will result in a DBRC::Error being raised. In addition, the file may also be encrypted on MS Windows systems, in which case the file will automatically be (temporarily) decrypted.

The format for XML (using the example above) is as follows:

<dbrc>
 <database name="mydb">
   <user>dan</user>
   <password>mypass</password>
   <driver>oracle</driver>
   <interval>30</interval>
   <timeout>10</timeout>
   <maximum_reconnects>2</maximum_reconnects>
 </database>
</dbrc>

The format for YAML is as follows:

- mydb:
  user: dan
  password: mypass
  driver: oracle
  interval: 30
  timeout: 10
  max_reconn: 2

The format for JSON is as follows:

[
  {
    "foo": {
      "user": "dan",
      "password": "mypass",
      "driver": "oracle",
      "interval": 30,
      "timeout": 10,
      "maximum_reconnects": 2
    }
  }
]

Constants

VERSION

The current version of this library, returned as a String.

Class Methods

DBRC.new(db, user = nil, dir = nil, gpg_options = nil)

The constructor takes one to three arguments. The first argument is the database name. This must be provided. If only the database name is passed, the module will look for the first database entry in the .dbrc file that matches.

The second argument, a user name, is optional. If it is passed, the module will look for the first entry in the .dbrc file where both the database and user name match.

The third argument, also optional, specifies the directory where DBRC will look for the .dbrc file. By default, it looks in the pwuid (present working user id) home directory. The rules for a .dbrc file still apply.

The fourth argument, if present, are options that are forwarded to the GPGME::Crypto.new constructor for GPG encrypted files. Typically this would at least be the :password option, but YMMV.

MS Windows users should read the "Notes" section for how your home directory is determined.

Instance Methods

DBRC#database

The name of the database. Note that the same entry can appear more than once, presumably because you have multiple user id's for the same database.

DBRC#db

An alias for DBRC#database.

DBRC#database=(database)

Sets the database to +database+. This is generally discouraged because it does not automatically reset the dsn.

DBRC#db=(database)

An alias for DBRC#database=.

DBRC#user

A valid user name for that database.

DBRC#user=(user)

Sets the user name to +user+.

DBRC#password

The password for that user.

DBRC#passwd

An alias for DBRC#password.

DBRC#password=(password)

Sets the password to +password+.

DBRC#passwd=(password)

An alias for DBRC#password=.

DBRC#driver

The driver type for that database (Oracle, MySql, etc).

DBRC#driver=(driver)

Sets the driver to +driver+. This use is discouraged because it does not reset the dsn.

DBRC#timeout

The timeout period for a connection before the attempt is dropped.

DBRC#time_out

An alias for DBRC#timeout, provided purely for the sake of backwards compatability.

DBRC#timeout=(int)

Sets the timeout value to +int+.

DBRC#maximum_reconnects

The maximum number of reconnect attempts that should be made for the the database. Presumablly, you would use this with a "retry" within a rescue block.

DBRC#max_reconn

An alias for DBRC#maximum_reconnects.

DBRC#maximum_reconnects=(max)

Sets the maximum number of reconnect attempts to +max+.

DBRC#max_reconn=(max)

An alias for DBRC#maximum_reconnects.

DBRC#interval

The number of seconds to wait before attempting to reconnect to the database again should a network/database glitch occur.

DBRC#interval=(int)

Sets the interval seconds between connection attempts.

DBRC#dsn

Returns a string in "dbi::" format.

DBRC#dsn=(dsn)

Sets the dsn string to +dsn+. This method is discouraged because it does not automatically reset the driver or database.

Canonical Example

# This is a basic template for how I do things:
require 'dbi'
require 'dbi/dbrc'
require 'timeout'

db = DBI::DBRC.new("somedb")
n = db.max_reconn

begin
  Timeout.timeout(db.timeout){
    DBI.connect(db.dsn, db.user, db.passwd)
  }
rescue DBI::Error
  n -= 1
  if n > 0
    sleep db.interval
    retry
  end
  raise
rescue TimeoutError
 # handle timeout error
end

Notes for MS Windows Users

To make your file hidden, right click on the .dbrc file in your Explorer window, select "Properties" and check the "Hidden" checkbox.

I was going to require that the .dbrc file be encrypted on MS Windows, but that may require an official "certificate", assigned to you by a third party, which is a bit much to expect. However, if the file is encrypted, DBRC will attempt to decrypt it, parse it, and encrypt it again when done parsing.

Summary

These methods don't really "do" anything. They're simply meant as a convenience mechanism for your database connections, plus a little bit of obfuscation (for passwords).

Adding your own configuration

If you want to add your own type of configuration file, you can still use the dbi-dbrc library. All you need to do is:

• subclass DBRC
• redefine the parse_dbrc_config_file method (a private method).

Take a look at the XML and YML subclasses in dbrc.rb for two examples that you can work from.

Future Plans

None at this time.

Known Bugs

I'm not positive about the dsn strings for databases other than Oracle. If it's not correct, please let me know.

Copyright

(C) Copyright 2002-2021, Daniel J. Berger, all rights reserved.

License

Apache-2.0

Warranty

This package is provided "as is" and without any express or implied warranties, including, without limitation, the implied warranties of merchantability and fitness for a particular purpose

Author

Daniel J. Berger